THE NEW LIGHT. 
K o H 
5o7 
plying its own conditions until something occurs to interfere with the process of 
oxidation. In this process magnesium is converted into magnesia, and then, 
but not till then, the resemblance to the lime light commences. The particles 
of magnesia become incandescent and intensely white and dazzling. By virtue 
of a power which they possess of being incapable of fusion, the heat is rejected 
as it were, and thrown out into the atmosphere in all directions ; not indeed as 
heat, but transformed as if by magic into rays of great brightness and splendour. 
A light is produced, which greatly resembles daylight, and which shows all sur¬ 
rounding objects in their natural and true colours. In the difference, then, here 
pointed out between the two lights, we observe a loophole of escape from some 
at least of the objections that have been urged against this mode of lighting for 
purposes of ordinary combustion. All cumbrous machinery is done away with, 
and the whole process is entirely free from danger. A parabolic or spheroid 
reflector will send the light to a great distance in any direction, whilst a pro¬ 
perly constructed lamp, without this addition, will modify and assist its general 
diffusiveness. 
In estimating, however, the probabilities of success as regards the introduction 
of magnesium for illuminating our public buildings, offices, and shops, two main 
points are open for consideration,—the character or quality of the light itself, 
and the cost incurred in its production. In the combustion of all hydro-carbons, 
such as coal gas, the products evolved are, for the most part carbonic acid and 
water, and these mingle with the atmosphere and pass off unperceived. The 
body oxidized is carbon, the result being a light of a soft yellow tinge, which 
can be looked at and examined by the eye without difficulty. The light is also 
clear and bright under proper management, and in the case of a common candle 
or lamp is both portable and safe. These qualities render this mode of lighting 
admirably adapted for ordinary use; but there are objections nevertheless, 
which it would be well if possible to get rid of.* 
In u ignition without combustion” we meet with a totally different result. 
Here the intensity is very great, the actinic or chemical ray being considered, 
in the case of magnesium, equal to that of daylight. Everything upon which 
the light falls is brilliantly illuminated, the reflection from white surfaces being 
correspondingly great—a matter of considerable importance, since there cannot 
be a doubt, that much injury is done to the eye when reading or working by the 
aid of an unsteady or indifferent light. It Avould not be difficult in the former 
case to regulate or lessen the intensity, if required, but we all know how dif¬ 
ficult, or rather how practically impossible it is, to brighten a flame issuing from 
a gas jet or common candle beyond its light-giving pover. But it is objected, 
that whilst lights “in which carbon constitutes the ignitable solid,” possess a 
power of diffusibility, which renders objects not directly opposed to the course of 
the rays more or less distinctly visible, “ the electric, lime, and magnesium lights 
possess none of this diffusiveness ; their rays seem to be projected with a force 
and velocity which deprives them of the power of diffusion. An object placed 
in the direct course of the rays is splendidly illuminated, and the rays are pro¬ 
jected to an immense distance ; but the shadows cast by intervening objects are 
intensely black, and the rays seem to pass through the atmosphere without pro¬ 
ducing much effect except upon that part which is in the course of the stream 
of light.” And herein would appear to reside the supposed cause of failure in 
the application of this light to ordinary illumination. u It is in no wise suitable 
to such a use.” Experiments, however, would seem to place magnesium in an 
exceptional position. Newspapers and books have been jffaced between the eye 
'* The means of testing the illuminating power and chemical purity of coal-gas, and the 
various methods adopted for measuring or determining the relative intensity of two lights, 
are given by Dr. Letheby in a very able lecture, published in the ‘Medical Times and 
Gazette,’ February 11th, 1865. 
